This invention relates generally to systems and arrangements for handling and testing packaged circuits, such as hybrid and integrated circuits, and more particularly, to a head for a handler having a sectioned rail system.
Integrated circuit and hybrid circuit handling systems have been employed for a number of years to facilitate testing of the devices in controlled environmental conditions, in automatic and semiautomatic modes. Of course, the testing of such electrical devices can be achieved in a manual system, but the throughout would be quite low, typically on the order of one or two units per minute. Fully automatic systems, however, are generally quite large, complex, and expensive. They are not readily adaptable to changes in the design of the circuit packages, but can achieve very high throughput.
There is a need in this industry for a handler arrangement which can achieve throughput rates on the order of a hundred or more electrical devices tested per hour, while achieving low initial cost, simplicity of construction, high modularity for ready adaptability to variations in the physical configuration of the devices to be tested, adaptability to the specific working and testing environment of the user, and compactness.
In order to achieve the appropriate environmental conditions to perform the required tests on the electrical devices to be tested, temperatures are required to range from typically as high as 155.degree. C. to -55.degree. C. In situation where the same handler unit conducts the testing in the cooled and heated modes, it is important that the handler not degrade rapidly as a result of repeated temperature variations. Such repeated wide-ranging temperature swings can impose thermal stresses upon the handler structure in the vicinity of the test site, which may result in a reduction in the life of the handler.
There is a particular problem which is present during cold testing, and which significantly reduces the throughput of a typical handler. Icing of the transport rails occurs when the dried, refrigerated cooling medium is vented from the test site and communicates with the external device transport rails. The external rails are generally at ambient temperature and exposed to the humidity in ambient air. The cold exhaust from the test site will cause the humidity in the air to precipitate as ice on the external rails, which ice eventually accumulates to the point where the electrical devices being tested will not be transportable therealong. There is, therefore, a need for a system which avoids icing on the transport rail.
It is a further problem with known handler systems that the control mechanism which governs the traffic flow and device handling will create stray fields which will affect the test process. Particularly in situations where the electrical device under test is either a low power device or operates at very high frequencies, stray magnetic or electrical fields generated by the control devices in the handler itself will result in erroneous test readings. A further source of potentially damaging electrical fields is the static charges which are developed as the electrical device under test, which may itself be packaged in a polymeric material, slides along the handler's transport rail.
It is, therefore, an object of this invention to provide a simple, economical, and compact handler system for electrical devices such as integrated and hybrid circuits.
It is another object of this invention to provide a handler arrangement which eliminates stray magnetic and electrical fields in the vicinity of the test site.
It is also an object of this invention to provide a handler system which can operate hot and cold testing environments.
It is a further object of this invention to provide a handler system which does not generate static charges and fields.
It is additionally an object of this invention to provide a handler system wherein transport rails external to the test site do not ice up during cold testing.
It is yet a further object of this invention to provide a handler system which achieves high throughout in a gravity feed transport arrangement.
It is still another object of this invention to provide a handler system which is characterized by low effective thermal mass at the test site.